Enable various eslint rules (#1773)

## Description:

Enable various eslint rules.

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

src/client/graphics/layers/ControlPanel.ts

@@ -18,7 +18,7 @@ export class ControlPanel extends LitElement implements Layer {
   public uiState: UIState;
 
   @state()
-  private attackRatio: number = 0.2;
+  private attackRatio = 0.2;
 
   @state()
   private _maxTroops: number;
@@ -35,7 +35,7 @@ export class ControlPanel extends LitElement implements Layer {
   @state()
   private _gold: Gold;
 
-  private _troopRateIsIncreasing: boolean = true;
+  private _troopRateIsIncreasing = true;
 
   private _lastTroopIncreaseRate: number;